MUTCD/Maryland
The Maryland Manual on Uniform Traffic Control Devices (MdMUTCD) is the standard for road signs, signals, and markings in the U.S. state of Maryland. It is developed by the Maryland State Highway Administration (SHA) "in substantial conformance to" the national MUTCD developed by the Federal Highway Administration.
The MdMUTCD defines the content and placement of traffic signs. Design specifications are detailed in the Maryland Standard Sign Book, the contents of which can be viewed online ([1]). The latest edition of the MdMUTCD was published in 2011 ([2]).
Usage in OpenStreetMap
A traffic sign specific to the MdMUTCD is mapped as a 
node tagged traffic_sign=US:MD:Z1-2, where "US:MD" is the state's ISO 3166 code and Z1-2 is the sign's alphanumeric designation.
Sign designations
Most standard sign or plaques in the MdMUTCD and in the Maryland Standard Sign Book are assigned an alphanumeric designation and organized by series, although there are a handful which deviate from convention. A sign designation generally follows the same format as in the national MUTCD and SHSD. However, some signs are specific to the MdMUTCD, such as signage related to the state's rail infrastructure, signage for highlighting general information and landmarks, and signage making reference to state laws. In most cases, sign codes that are specific to the Maryland standard duplicate a corresponding federal sign code and append a number in parentheses, for example, D1-1(1) describes a Maryland standard destination panel sign.
The MdMUTCD further highlights which signs from the federal MUTCD standard are only permitted on roadways which are not maintained by the State Highway Administration, and federal signs which are not permitted for use in Maryland altogether. The MdMUTCD is comprehensive in that it includes some signage which is specific to the Baltimore and Washington, D.C. metropolitan areas. Despite the fact that the State Highway Administration does not maintain any of Baltimore City's roadways, the Baltimore City Department of Transportation complies with the MdMUTCD for the most part with only a few small additions. Note that the MdMUTCD standards related to county routes or county guide signs are not applicable to Baltimore City as it is not a county, and that the many federally coded sign standards which are not permitted for use on state-operated roadways are eligible for use on any roadway in Baltimore City, including those that are nominally part of a state highway route.
Signs by series
- Main article: MUTCD#Signs by series
The following pages contain a correspondence between MdMUTCD-specific signs and their most likely tagging in OpenStreetMap:
- Series D – Destination and Distance
- Series E – Exit Signs
- Series EM – Emergency Management and Civil Defense Signs
- Series G – Work Zone
- Series I – General Information Signs
- Series M – Marker Signs
- Series OM – Object Marker
- Series R – Regulatory Signs
- Series S – School Signs
- Series W – Warning Signs
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The MdMUTCD standard sign book also includes a few paddles and panels which are not categorized in manner that fits into the lettered series listed above. (The single vertical panel specification has a "VP" prefix, but the paddles and horizontal panels have been given codes without prefixes.) These have functions related to the Object Marker and Work Zone categories.
Jurisdictions within Maryland
Baltimore City
Baltimore has just two additional standardized signs specified in the Baltimore City Department of Transportation Code. These are a tree preservation area sign (BC 701.34) and a push-button-to-cross sign (BC 890.11) for use at signalized pedestrian crossings.
As the "County Line" general information signs specified by MdMUTCD codes I-2(1) and I-2(2) are not applicable to marking Baltimore City limits, the city Department of Transportation specifies City Gateway signs at many major entry/exit points around the city boundary ([3]). These vary but most have some common characteristics in form, with most of them being "Outlier Pylon Style" signs, which are towers along the roadside bearing the name Baltimore in bold, red all-caps lettering.
Due to the fact that the state of Maryland does not maintain any Baltimore City roadways, including those nominally part of state and interstate highway routes, there is more leeway as to what signs from the federal MUTCD standard are permitted for use on major corridors. The state does however maintain most of the city's public transportation infrastructure, and much of the signage which may seem specific to Baltimore regarding railway crossings and buses is in fact produced by the state of Maryland. Outside of design standards, there are a number of idiosyncrasies in the use and distribution of traffic signs within Baltimore City. Most interstate and state highway routes are unsigned or very sporadically signed, with I-83 being the most notable exception, and it is common to see a number of ad hoc signs which do not originate from any particular standard.
